Background: Multiple large scale randomized controlled trials have shown that in people with impaired glucose tolerance, between 40 and 60% of cases of Type 2 diabetes can be prevented with lifestyles interventions that emphasize diet, exercise and weight loss. Despite the strong evidence base supporting preventability, the incidence of diabetes continues to increase. In the US, almost 2 million people were newly diagnosed with type 2 diabetes in 2010. VA MOVE! does not specifically target those with pre-diabetes and most veterans referred to VA MOVE! who don't already have a diagnosis of diabetes do not know if they are pre-diabetic or not. With a few exceptions, lifestyle modification interventions that target individuals with pre-diabetes and follow the Diabetes Prevention Program curriculum are not available to veterans with pre-diabetes in the VA. This project will build on two pre- existing projects, the VA Diabetes Prevention clinical demonstration project funded by our partners at VA National Center for Health Promotion and Disease Prevention (NCP) and the QUERI funded RRP titled: VA Diabetes Prevention: Epidemiology of Pre-Diabetes and Implementation Pilot. Methods: The evaluation components proposed in this SDP application represent a Hybrid Type 3 mixed methods implementation evaluation. Consistent with this goal, our research team has worked collaboratively with NCP to identify three specific implementation-focused research questions, the answers to which will inform national implementation of the DPP in the VA. There are three distinct research components corresponding to the three specific aims in this research plan: an implementation evaluation, a mediation analysis of components that differ between VA MOVE! and VA DPP, and a cost- effectiveness/budget impact analysis. Veterans who are referred to VA MOVE! at one of three VA medical centers will be screened for pre-diabetes. Those who meet inclusion criteria will be assigned using a systematic sampling to either VA DPP or VA MOVE! Participants will be tracked for 1 year following assignment to evaluate weight loss and session attendance. Participants will also be invited to complete two surveys, one at baseline and one at a 12 month follow-up visit. A subset of participants will be interviewed for qualitative data to support quantitative results and to inform the implementation analysis. Additional staff interviews will be coded using the CFIR and RE-AIM implementation framework to guide future implementation strategies. Objective 1. Test an implementation strategy and identify barriers and facilitators to implementation of the VA DPP at three VA medical centers using a mixed methods approach that is informed by the CFIR and RE- AIM implementation frameworks. 2. Test for mediation of intervention effect on weight loss by constructs that are addressed differently in VA MOVE! and the VA DPP including group cohesion, intervention intensity, outcome expectations, goal awareness and commitment, and self-regulation skills. 3. Conduct cost-effectiveness and budget impact analyses of implementing the VA DPP broadly in the VA from the perspective of the health system.